Detection of fine asbestos fibers using fluorescently labeled asbestos-binding proteins in talc

Asbestos contamination in common materials, including powdered talc used in manufacturing cosmetics, pharma-ceuticals, and baby powder, is of great public concern. The use of polarized light microscopy (PLM) for asbestos detection is limited because it cannot detect fibers with diameters in the nano range. Furthermore, the use of electron microscopy (EM), the preferred method for determining asbestos contamination in talc, is hindered by a rather complicated and laborious process. Fluorescence microscopy (FM) is a simple analytical tool in mod-ern life sciences, especially given its superior sensitivity and selectivity; however, it is rarely used for inorganic materials. Previously, we demonstrated that airborne asbestos fibers were fluorescently visualized under FM us -ing fluorescently labeled asbestos-binding proteins. Here, we evaluated the FM method's feasibility in detecting fine asbestos fibers in powdered talc. The limit of detection of the fiber diameter of asbestos was approximately 0.06 & mu;m using FM. The FM method's sensitivity surpassed that of PLM and approached that of EM, and thus, it can detect nano-scale fibers. Notably, the FM method enabled the selective visualization of asbestos fibers, including those hidden beneath numerous talc particles. A point counting method using FM images enabled a semi-quantitative analysis of 0.01-1.0% (w/w) asbestos contamination in talc.

Automated summary

In this study, we evaluated the feasibility of using fluorescence microscopy (FM) for detecting fine asbestos fibers in powdered talc. FM showed superior sensitivity in detecting nano-scale fibers and enabled the selective visualization of asbestos fibers, even when hidden beneath numerous talc particles. A semi-quantitative analysis of asbestos contamination in talc was achieved using a point counting method with FM images.